marekm

Thanks Duncan. So decompression issues aside, the bigger concern is the DIN reg working lose once the O2 system depressurises, and then the O2 venting as you turn the O2 tank valve back on. I heard Mark Chase's account of this happening during a training course so it may be quite common.

Next question, should the ball valve shut down the O2 supply to the orifice only, or the manual O2 inject button as well. I can see the rational of shutting down the O2 orifice if the IP starts creeping on the O2 first stage, resulting in the PO2 rising. Shutting down the O2 orifice leaves you with the ability to keep running in pure mCCR mode.

However, I have read about some people using the shutoff valve to shut down the supply pressure to the manual O2 injection just incase the manual inject button jams on. Any point in doing that?

Cheers.

-Marek